The present invention relates to a starting and control method for a brushless DC motor, especially a sensorless type motor.
In a brushless DC motor of the prior art, a rotation position of a rotor is detected by a detector such as hall-effect switch, and current is supplied to a stator coil of the motor at most the suitable relative position with respect to the rotor and the stator.
In recent years, it is expected to miniaturize and thin the brushless DC motor. Therefore, it is difficult to provide the detector such as hall-effect switch within the motor.
Further, there is difficulty in that the detector, such as hall-effect switch, and the parts, such as printed boards, make the motor expensive.
It is a purpose of the present invention to provide a brushless DC motor which is small size, thin and inexpensive.
Starting and control method for brushless DC motor in accordance with the present invention comprises steps of,
starting the motor by exciting the stator with open loop circuit, and
accelerating the motor according to detected counter-electromotive force of the stator coil to reach rated rotation,
thereby enabling to start, accelerate and rated rotate the motor without a detector of rotor position.
While the novel features of the invention are set forth particularly in the appended claims, the invention, both as to organization and content, will be better understood and appreciated, along with other objects and features thereof, from the following detailed description taken in conjunction with the drawings.